Journal of Geophysical Research: Space Physics最新文献

{"title":"A Case Study of Thermospheric Exospheric Temperature Responses During the G-Condition at Mohe and Beijing Stations","authors":"Shaoyang Li,&nbsp;Zhipeng Ren,&nbsp;Tingting Yu,&nbsp;Biqiang Zhao,&nbsp;Libo Liu,&nbsp;Guozhu Li,&nbsp;Xinan Yue,&nbsp;Yong Wei,&nbsp;Lianhuan Hu","doi":"10.1029/2024JA032653","DOIUrl":"https://doi.org/10.1029/2024JA032653","url":null,"abstract":"<p>The G-condition (NmF₂ ≤ NmF₁) was observed by ground-based ionosondes at Mohe and Beijing during the geomagnetic storm occurred on 23 and 24 April 2023. We studied exospheric temperature (Tex) responses during the G-condition. Tex was derived from electron density (Ne) profiles (∼150–200 km) by the method proposed by Li et al. (2023, https://doi.org/10.1029/2022ja030988). The retrieved Tex showed obvious enhancements, with relative deviation of ∼10%–35% and ∼3%–20% at Mohe and Beijing, respectively. Additionally, chemical reaction rate increased by ∼15%–100% and ∼13%–30%, and O/N₂ decreased by ∼17%–35% and ∼23%–30% at Mohe and Beijing, respectively. Under photochemical equilibrium assumption, peak Ne is inversely proportional to chemical reaction rate and proportional to O/N₂. Increased chemical reaction rate and decreased O/N₂ indicate a decrease in peak Ne. Compared to the increased Tex, the relative enhancement in Tex is more significantly associated with the G-condition, with relative deviation above ∼10% during the G-condition.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 10","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142429519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Longitudinal Variations of Energetic Electrons Scattered by NWC Transmitter: DEMETER Observations","authors":"Yangxizi Liu,&nbsp;Zheng Xiang,&nbsp;Binbin Ni,&nbsp;Chen Zhou,&nbsp;Jianhang Wang,&nbsp;Deyu Guo,&nbsp;Junhu Dong,&nbsp;Jingle Hu,&nbsp;Haozhi Guo","doi":"10.1029/2024JA032975","DOIUrl":"https://doi.org/10.1029/2024JA032975","url":null,"abstract":"<p>Low-Earth orbit (LEO) satellites often observe wisp-like energy spectra, characterized by lower energies at higher <i>L</i> values of energetic electrons, resulting from the scattering effect of the narrow-band artificial transmitter signals. Typically, the flux levels of wisp energy spectra increase as they approach the South Atlantic Anomaly (SAA). Here, we report, for the first time, the longitudinal variations of wisp positions in the energy-<i>L</i> coordinate based on observations from the DEMETER satellite. The <i>L</i>-values of wisps decrease at the longitudes &lt;180° and increase at the longitudes &gt;180°. By considering the satellite's orbital characteristics, we found that the longitudinal variations of wisp are essentially the MLT-dependent radial transport of electrons. This finding indicates that the electron drift paths can be modified within a single drift period. We propose a duskward convection electric field as a potential mechanism to explain the longitudinal variations of wisps. By assuming a uniform duskward convection electric field with an amplitude of ∼1.5 mV/m, our simulations can reasonably reproduce the longitudinal variations of wisps observed in the southern hemisphere on 21 March 2009. Our results support the existence of a convection electric field in the inner belt and suggest that this electric field significantly contributes to the variations in energies and <i>L</i> values of energetic electrons within one drift period.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 10","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA032975","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142429294","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Rapid Transport of Energetic Electrons to Low \u0000 \u0000 \u0000 L\u0000 \u0000 $L$\u0000 -Shells: The Key Role of Electric Fields","authors":"Anton Artemyev,&nbsp;Yukitoshi Nishimura,&nbsp;Vassilis Angelopoulos,&nbsp;Xiao-Jia Zhang,&nbsp;Jacob Bortnik","doi":"10.1029/2024JA033136","DOIUrl":"https://doi.org/10.1029/2024JA033136","url":null,"abstract":"<p>The dynamics of the outer radiation belt are traditionally associated with wave-particle resonant interactions, which provide local electron acceleration and losses through very low-frequency waves, and electron radial transport by ultra-low frequency waves. However, these processes cannot explain observations of rapid radial transport of energetic electrons (on a time-scale of a couple of hours), deep into the inner magnetosphere (down to <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>L</mi>\u0000 <mo>∼</mo>\u0000 <mn>2</mn>\u0000 </mrow>\u0000 <annotation> $Lsim 2$</annotation>\u0000 </semantics></math>, mapping to <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>∼</mo>\u0000 <mn>45</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> ${sim} 45{}^{circ}$</annotation>\u0000 </semantics></math> magnetic latitude in the ionosphere). This transport is likely associated with strong convection electric fields forming around the plasmapause. To investigate these rapid, low-latitude electron transport, we combine low-altitude observations of energetic electron fluxes by the ELFIN CubeSats and DMSP satellites, SuperDARN measurements of ionospheric plasma flows (electric fields), and equatorial measurements of energetic electrons and electric fields by THEMIS. Our findings demonstrate that the rapid filling of the slot region by <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mo>&lt;</mo>\u0000 <mn>300</mn>\u0000 </mrow>\u0000 <annotation> ${&lt; } 300$</annotation>\u0000 </semantics></math> keV electrons is directly associated with electric field penetration to low latitudes (down to <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>40</mn>\u0000 <mo>−</mo>\u0000 <mn>50</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> $40-50{}^{circ}$</annotation>\u0000 </semantics></math>). The proposed electron transport scenario, the direct penetration of energetic electrons by strong, localized electric fields, underscores the importance of ionosphere-magnetosphere coupling in radiation belt dynamics.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 10","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-10-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142429619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"O-Mode Instability for Non-Thermal Continuum Radiation Generated Near the Plasmapause","authors":"Chio Z. Cheng,&nbsp;Eun-Hwa Kim,&nbsp;Scott A. Boardsen,&nbsp;Iver H. Cairns,&nbsp;Jay R. Johnson","doi":"10.1029/2024JA032626","DOIUrl":"https://doi.org/10.1029/2024JA032626","url":null,"abstract":"<p>Analysis of the ordinary mode (O-mode) instability is performed to comprehend the nonthermal continuum (NTC) radiation near the plasmapause, taking into account the relativistic wave-electron resonance effect. The energy source is the anisotropy in the velocity of the minority suprathermal electron population. Numerical solutions demonstrate that the O-mode can be unstable with multiple narrow frequency bands located close to harmonics of the electron cyclotron frequency above the local electron plasma frequency. These waves have narrow beaming angle bands of nearly <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mn>90</mn>\u0000 <mo>°</mo>\u0000 </mrow>\u0000 <annotation> $90{}^{circ}$</annotation>\u0000 </semantics></math> relative to the ambient magnetic field. Our findings indicate that NTC radiation generated by this wave-electron resonance instability near the plasmapause can propagate nearer to the magnetic equator with multiple harmonics, which is in agreement with a recent statistical study using Van Allen Probes.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 10","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA032626","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142429437","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of Storm-Time Winds on Ionospheric Pre-Midnight Equatorial Plasma Bubbles Over South America as Observed by ICON and GOLD","authors":"Gilda González,&nbsp;Yen-Jung Wu,&nbsp;L. Claire Gasque,&nbsp;Colin C. Triplett,&nbsp;Brian J. Harding,&nbsp;Thomas J. Immel","doi":"10.1029/2024JA033111","DOIUrl":"https://doi.org/10.1029/2024JA033111","url":null,"abstract":"<p>This study uses satellite measurements of plasma densities and thermospheric winds to analyze the effects of the November 2021 geomagnetic storm on ionospheric pre-midnight topside plasma bubbles over South America. Using observations from the Ionospheric Connection Explorer (ICON) and the Global-scale Observations of the Limb and Disk (GOLD) satellites, we find that pre-midnight topside plasma bubbles were inhibited over eastern South America during the recovery phase of the storm. This is particularly notable because of the otherwise high occurrence rate of plasma bubbles at these longitudes during this season. This inhibition coincided with the recovery phase of the geomagnetic storm, marked by a northward turning of the z-component of the interplanetary magnetic field (IMFBz) and quiet-time values of the SuperMAG Auroral Electrojet Index (SME). We observed a westward turning of the zonal wind before the bubble inhibition, so we conclude the inhibition of topside plasma bubbles is likely related to a westward disturbance dynamo electric field (DDEF) causing a downward <span></span><math>\u0000 <semantics>\u0000 <mrow>\u0000 <mi>E</mi>\u0000 <mo>×</mo>\u0000 <mi>B</mi>\u0000 </mrow>\u0000 <annotation> $mathbf{E}times mathbf{B}$</annotation>\u0000 </semantics></math> drift and suppress the growth of the instability responsible for bubble development. Contrary to theoretical predictions, we do not observe notable changes to the meridional wind during the event. These results provide new insights into the ionosphere-thermosphere system's response to geomagnetic storms and highlight the role of wind patterns in inhibiting ionospheric irregularities, contributing to better predictive models for these phenomena.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 10","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033111","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142429441","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Location of Geomagnetic Disturbances in Relation to the Field Aligned Current Boundary","authors":"G. E. Bower,&nbsp;S. Imber,&nbsp;S. E. Milan,&nbsp;A. Schillings,&nbsp;A. L. Fleetham,&nbsp;J. W. Gjerloev","doi":"10.1029/2024JA033039","DOIUrl":"https://doi.org/10.1029/2024JA033039","url":null,"abstract":"<p>Geomagnetic disturbances (GMDs) are rapid fluctuations in the strength and direction of the magnetic field near the surface of the Earth which can cause electric currents to be induced in the ground. The geomagnetically induced currents (GICs) can cause damage to pipelines and power grids. A detection algorithm has been developed to identify rapid changes in 10 s averaged magnetometer data. This higher resolution data is important in capturing the most rapid changes associated with extreme GIC events. The algorithm has been used on an array of ground-based magnetometers from SuperMAG data from 2010 to 2022, creating a new list of global GMDs. Data from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) is used to place the observed GMDs in the context of the global pattern of magnetosphere-ionosphere field-aligned currents (FACs). A dawn sector population of GMDs is found to lie near the boundary between the region 1 and region 2 FACs, while a pre-midnight sector population is found to occur poleward of the FAC boundary on region 1 upward FACs. It is also shown that the latitude of the GMDs expands with the FAC boundary and their occurrence peaks around 77° magnetic latitude.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 10","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA033039","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142429440","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reimei Satellite Observations of Alfvénic Interaction Modulating Inverted-V Electrons and Filamentary Auroral Forms at the Poleward Edge of a Discrete Arc","authors":"Masafumi Hirahara,&nbsp;Yusuke Ebihara,&nbsp;Naritoshi Kitamura,&nbsp;Takeshi Sakanoi,&nbsp;Kazushi Asamura,&nbsp;Taku Takada,&nbsp;Hirobumi Saito","doi":"10.1029/2024JA032650","DOIUrl":"https://doi.org/10.1029/2024JA032650","url":null,"abstract":"<p>We present an event based on Reimei satellite observations in the low-altitude midnight auroral region, showing that intense and clear energy-dispersed electron precipitations, repetitively generated by field-aligned accelerations due to dispersive Alfvén waves, were modulating inverted-V electrons. These Alfvénic electrons had peak energies equal to or slightly larger than those of the inverted-Vs and were associated with the filamentary auroral forms rapidly streaming at the poleward edge of a broad discrete arc. This arc was caused by the inverted-V accompanied by ion depletions produced by quasi-electrostatic parallel potential drop. Assuming instantaneous electron accelerations over a wide energy range in a single location and a simple time-of-flight effect for the energy-time dispersions, the Alfvénic source distances were estimated 1,500 ± 500 km above the satellite altitude of ∼676 km, a lower bound since the interaction locations are realistically distributed in altitudinally extended regions. The electron characteristics in detailed energy-pitch angle distributions obtained at high time resolution can be categorized into: (a) original inverted-V fluxes energized by quasi-electrostatic upward electric field, (b) accelerated and decelerated/reduced inverted-V fluxes, (c) field-aligned energy-dispersed precipitations accelerated by dispersive Alfvén waves, and (d) upwelling secondary components effectively produced by the field-aligned precipitations particularly at energies of a few tens of eV. This event is useful to reveal the interactions between the inverted-V and Alfvénic electrons and their related ionospheric effects in the magnetosphere-ionosphere coupling processes. The detailed energy-pitch angle distributions presented here provide constraints for models of these interactions and processes.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 10","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1029/2024JA032650","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142429412","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The ROC Curve Examination on Traveling Ionospheric Disturbances in FORMOSAT-7/COSMIC-2 IVM Ion Density Triggered by the 15 January 2022 Tonga Volcanic Eruption","authors":"Jann-Yenq Liu,&nbsp;Ching-Chung Cheng,&nbsp;Po-Han Lee,&nbsp;Tien-Chi Liu,&nbsp;Chi-Yen Lin,&nbsp;Charles Chien-Hung Lin,&nbsp;Kevin Kan","doi":"10.1029/2024JA033198","DOIUrl":"https://doi.org/10.1029/2024JA033198","url":null,"abstract":"<p>The receiver operating characteristic (ROC) and the area under the curve (AUC), initially developed for signal processing and psychology, are a test for assessing the performance of a binary classification problem at varying threshold values. The ion density (N_i) observed by FORMOSAT-7/COSMIC-2 is used to study traveling ionospheric disturbances (TIDs) triggered by the 15 January 2022 Tonga volcanic eruption. We examine parameters of N_i, differential N_i, and standard deviation N_i (STD_N_i) in January 2022, simulate TID wavefronts traveling with various speeds from 10 to 1,000 m/s, and apply the ROC curve to globally identify the significance of TIDs in STD_Ni triggered by the volcanic eruption. ROC and AUC results show that in addition to TIDs related to tsunami/tropospheric Lamb waves and a series of fast-moving waves with propagation speeds of 180–350 and 450–600 m/s, respectively, those long-lasting low-speeds less than 70 m/s and high-speeds about 690, 860, and 990 m/s meet 95% statistical significance, which confirms TIDs being detected. These show that the FORMOSAT-7/COSMIC-2 ion density can be used to globally detect various TIDs triggered by the Tonga volcanic eruption. The ROC test results also show a potential use case for detecting other geophysical signals in future applications.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 10","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142429443","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Different Origin Field-Aligned Currents and Their Relationship With Auroral Intensity","authors":"B. H. Qu,&nbsp;J. Y. Lu,&nbsp;Z. W. Wang,&nbsp;J. J. Liu,&nbsp;M. Wang,&nbsp;J. Y. Li,&nbsp;H. Zhang","doi":"10.1029/2024JA032927","DOIUrl":"https://doi.org/10.1029/2024JA032927","url":null,"abstract":"<p>The ionospheric field-aligned current (FAC) consists of three components related to ionospheric vortices and gradients of Pedersen and Hall conductances, with the first term being of magnetospheric origin and the latter two being of ionospheric origin (Eq. 1). We calculate each of them between 2010 and 2016 using line-of-sight velocity data from the Super Dual Auroral Radar Network radar and auroral electron precipitation data from the Defense Meteorological Satellite Program. Then, we investigate the contribution of each FAC component, as well as the relationship between each FAC component and auroral activity. Our result shows that ionospheric-origin FACs contribute up to 54% (dawn) and 42% (dusk) within the auroral oval. Both magnetospheric-origin FACs and ionospheric-origin FACs initially increase and then stabilize as the SuperMAG electrojet (SME) index increases. After stabilization, these two currents have almost equally important roles, with an average contribution rate of 56% and 44%, respectively. Additionally, the ionospheric-origin FACs are found to have a higher dependency on auroral intensity. We also find that magnetospheric-origin FACs exhibit distribution patterns similar to the R1/R2 FAC systems because their directions are determined by vorticities. When the SME index exceeds 200 nT, the contribution from the Pedersen conductance gradient consistently exhibits downward currents near 70° magnetic latitude in the dusk and predawn sectors due to the combined effects of velocities and Pedersen conductance gradients. However, the distribution pattern from the Hall conductance gradient is not so clear due to the uncertainty in the angle between velocity and Hall conductance gradient.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 10","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142429414","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A Statistical Examination of Interactions Between 1-Hz Whistler Waves and Ions in the Earth's Foreshock","authors":"Shan Wang,&nbsp;Jing-Huan Li,&nbsp;Li Li,&nbsp;Xu-Zhi Zhou,&nbsp;Yoshiharu Omura,&nbsp;Jiu-Tong Zhao,&nbsp;Zhi-Yang Liu,&nbsp;Qiu-Gang Zong,&nbsp;Hui Zhang,&nbsp;Chao Yue","doi":"10.1029/2024JA032960","DOIUrl":"https://doi.org/10.1029/2024JA032960","url":null,"abstract":"<p>The 1 Hz whistler wave precursors attached to shock-like structures are often observed in the foreshock. Using observations from the Magnetospheric Multiscale mission, we investigate the interactions between 1 Hz waves and ions. Incoming solar wind ions do not cyclotron-resonate with the wave, since typically the wave is right-handed in their frame. We demonstrate that solar wind ions commonly exhibit 180° gyro-phase bunching from the wave magnetic field, understanding it with a reconciled linear theory and non-linear trapping theory for non-cyclotron-resonant modulations. Along the longitudinal direction, solar wind ions experience Landau resonance, exhibiting either modulations at small wave potentials or trapping in phase-space holes at large potentials. The results also improve our understanding of foreshock structure evolution and 1 Hz wave excitation. Shock-like structures start with having incoming solar wind and remotely reflected ions from further downstream. The ion-scale 1 Hz waves can already appear during this stage. The excitation may be due to shock-like dispersive radiation or kinetic instabilities resonant with these remotely reflected ions. Ions reflected by local shock-like structures occur later, so they are not always necessary for generating 1 Hz waves. The wave leads to ion reflection further upstream, which may cause reformation of shock-like structures. In one event, locally reflected ions exhibit non-cyclotron-resonant modulation in the early stage, and later approach the anomalous cyclotron resonant condition with gyro-phases ∼270°. The latter is possibly due to nonlinear trapping in regions with an upstream-pointing magnetic field gradient, linked to reformation. Some additional special features, such as frequency dispersions, are observed, encouraging further investigations.</p>","PeriodicalId":15894,"journal":{"name":"Journal of Geophysical Research: Space Physics","volume":"129 10","pages":""},"PeriodicalIF":2.6,"publicationDate":"2024-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142429413","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}